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arXiv · 2507.00277

Towards Lazy B-Trees

Casper Moldrup Rysgaard·Sebastian Wild
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Abstract

Lazy search trees (Sandlund & Wild FOCS 2020, Sandlund & Zhang SODA 2022) are sorted dictionaries whose update and query performance smoothly interpolates between that of efficient priority queues and binary search trees - automatically, depending on actual use; no adjustments are necessary to the data structure to realize the cost savings. In this paper, we design lazy B-trees, a variant of lazy search trees suitable for external memory that generalizes the speedup of B-trees over binary search trees wrt. input/output operations to the same smooth interpolation regime. A key technical difficulty to overcome is the lack of a (fully satisfactory) external variant of biased search trees, on which lazy search trees crucially rely. We give a construction for a subset of performance guarantees sufficient to realize external-memory lazy search trees, which we deem of independent interest.

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Casper Moldrup Rysgaard, Sebastian Wild. 2025-12-16. Towards Lazy B-Trees. https://doi.org/10.4230/lipics.mfcs.2025.87

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